Process of preparing hydrocyanic acid



Patented Aug. 23, 1932 23 1.13:

UNITED STATES noBERT n. FULTON, or PITTSBURGH, PENNSYLVANIA, nssrenoia To---Trrn Korrnns COMPANY or DELAWARE, A CORPORATION or DELAWARE PROCESS or PREPARING HYDROCYANIG ACID No Drawing.

In accordance with the present process,-

ammonia gas and hydrocarbon vapors are thoroughly mixed together in such manner,

that a mixture is formed containing these substances in the proportions which take part in the complete reaction between them, when forming hydrocyanic acid, and this mixture is passed into the reaction chamber over a very effective catalyst.-

It is of fundamental importance that the reacting substances should i be properly mixed before they are subjected to heat and passed over the contact mass. Only when the substances are mixed in correct molecular proportions can the maximum yields be obtained with minimum amounts of objectionable by-products. 1

An important feature of the present invention is the manner in which the ammonia and hydrocarbon are mixed. This is brought about by bubbling ammonia gas, preferably anhydrous, through a hydrocarbon, which is liquid at ordinary temperatures, such as benzene or toluene, under such conditions that the resultant gas mixture contains the desired proportions by volume.

By way of example, anhydrous ammonia.

gas is bubbled through benzene contained in a suitable absorption apparatus and the benzene kept at a temperature preferably between 28 and 30 C. at atmospheric pressure. At about 28 0., the vapor tension of benzene is such that the resultant gas mixture contains one volume of benzene and six volumes of ammonia.

Application filed June 28, 1929. .Serial No. 374,613.

The ammonia-benzene mixture is ledover a catalyst heated preferably to 1100 to 1150 'l C. The hydrocyanic acid formed ab-v sorbed in sodium hydroxide to form sodium cyanide, or in a mixture of milk of limei'and sulphur to form calcium thiocyanate.

, The react ons involved are 1) 6NH3 (3 H.3 GHCN 9H2 When, for instance, "toluene. is "used,

heated to from 50 C. to 55 C; and prefer-Q ably kept within this temperature range at atmospheric ress r while passing" ammonia through it toobtain a mixture of proper proportions, namely, jonelvolume of toluone to seven volumes of ammonia. 5 The'inix-v ture is then permitted toreact in the presence of a catalyst and the process carriedon' as.

set forth above in the caseof benzene'lf The following reactlon between toluene and ammonla occurs,: 7 r i T c nsnlvn srnox 11H, ,1

.Various catalysts including a mixture of granular alumina-and granular fused quartz, 7

or pumice coated with alumina,1orcoke', etc., may be used. However, the best results'are obtained by the use of a eatalyst'preparedfin the following manner :A soluble aluminum saltsuch as aluminum 'nitrateis dissolved in 1' waterv to .form' a dilute solution, and any desired amount of a micropor'ous silicious mineral powder as for instance tripoli or diatomaceous earth isv stirred into the solution. Thereafter aluminum hydroxide is precipitated by the addition of ammonium carbonate in suflicient amount to entirely precipitate the aluminum as aluminum hydroxide. Ammonium hydroxide may be used instead of ammoniumcarbonate, or any other compound may be used which when heated with freshly precipitated aluminum hydroxide, will pass off and'at the same time tend to form pores in the latter. The precipitate is filtered without washing and dried slowly. at a low tem structure and it is apparently this compound which has the desired catalytic effect.

The presence upon the above catalyst of carboniiepesited 'frkmxthe benzene vap 0!;- fli1 ther increases the'activityof the catalyst In place of pure benzene, a commercial impurities such, as xylene,

tarry matter. may

ben zoleooataining toluene, pyridinean used. In fact any substantially pure liquid hydrocarbon may beaused and; ate1i'th proper temperature is determined at which the desired proportions of amomnia and hydroc-arbon may be obtained in the manner set forth, the reaction will proceed rapidly f and efiiciently; f I claimasmy invention:

ILIna rocessiof manufacturing hydro- "cyanic' acifrom a hydrocarbon and arm monia, the step consisting of bubbling am monia gas through a liquid hydrocarbon maintained at aE-itemperature and; rejssure at a. mixtureloifammon i a and hydrocarbon vapor is, formed in. the proportions which react completely to form hydrocyanic 7 acid.

" i' cid }pressure to formfa, mixture of. ammonia and enzene vapor infthe proportions whi'ch-re-fl act completely to form hydrocyanic acid; I 3; I'na process of manufacturingihydrge 1 throng iliquid' benz ene maintained at sub.-. stantially 28"G-to 30 Ggya tmospheric cyanic acid from a hydrocarbon and ammonia, the step consisting of*"passing ammonia through, liquid toluenemaintained at substantially 50.9 C; to 55C. atatmos. pheric pressure to'f'or-m aimixtu-reofsam moniaand toluene vapor in the proportions which reactrcompletely' to form'hydrocyanic -ac1- ".n r v I Intestimony whereof, I have hereunto subscribed'my name thisn21st day of J 11119 1929. 1 l ROBERT: Ru FULTON;

I 2.11m prd e sloi manufaeturing'hydro y "r'om-a'hydrocarbon and'arnmonia, theste consisting of passing ammOIIia gasf 

